The present invention relates to ultrasound imaging with catheters. In particular, two- or three-dimensional imaging is provided with an array in a catheter.
In the AcuNav™ catheter, a 64 element array of elements extends along a longitudinal axis of the catheter. The array is positioned at a tip portion for scanning a two-dimensional region or plane along the longitudinal axis. Other catheters have been proposed where one or more elements are rotated within the catheter about the longitudinal axis to scan in a plane perpendicular to the axis.
During use, a catheter is inserted within the circulatory system of the patient. The flexibility along the catheter may vary as a function of position, such as having a more flexible tip portion for off-axis bending while guiding the catheter. The catheter is guided through the circulatory system to position the ultrasound transducer adjacent to a desired location. Guide wires or rotation of the entire catheter are used to position the image plane at the desired location. Various stresses and strains may cause bending and slight twisting along the catheter. Images are then generated of the desired location.
By only scanning along a two-dimensional plane, identifying the desired location may be more difficult. Three-dimensional imaging has been proposed for more easily identifying a region of interest. Since catheters are small, such as having a 3 mm diameter, it may be difficult to position a two-dimensional array within the catheter. Three-dimensional imaging may be provided by moving the imaging plane of the one-dimensional array. For example, the catheter is slowly inserted further or withdrawn from a current position to create a plurality of cross sectional scans using a rotating array. However, the imaging plane position for accurate or higher resolution three-dimensional reconstruction may be difficult.